UNITED NATIONS -- Sudan agreed yesterday to allow more than 3,000 heavily armed UN and African peacekeepers in Darfur to reinforce a beleaguered African Union force of 7,000 that has struggled to prevent the slaughter of hundreds of thousands of civilians during the past four years. But UN officials said it could be more than six months before foreign troops land in Darfur.

Still, yesterday's agreement marked a critical new phase in a plan to gradually expand the United Nations' presence and power in Darfur, where government-backed militia stand accused of killing 200,000 to 400,000 civilians and driving more than 2.5 million from their homes. The United Nations ultimately hopes to oversee a joint UN-AU force with more than 20,000 soldiers, police, and civil servants.

()UN officials say yesterday's announcement would shift attention from Khartoum to the UN effort to assemble a peacekeeping force. The top UN peacekeeping official, Jean-Marie Guihenno, will meet Thursday with representatives of governments considering sending troops to Darfur. So far, the United Nations has faced resistance from potential contributing countries who are loath to have their troops serve under the African Union. UN military planners are also awaiting the arrival of some 1,500 AU troops to Darfur to provide additional security for the new force.

() Sudan has opposed a full-fledged UN mission in Darfur out of concern that it would arrest Sudanese officials accused of war crimes by the International Criminal Court. It has also raised concern about the right of foreign peacekeepers to use force to protect civilians. "It is our responsibility to protect the civilians; nobody can take it from us," said Sudan's ambassador to the United Nations, Abdalmahmood Abdalhaleem Mohamad. "This is a sovereign right."